Load Break Switch Grounding and Inspection Best Practice

[vtpower]

Hi Folks,
I am at an electric utility and an item that has continued to come up at our Union Labor Management meetings is if we are doing adequate initial grounding testing and adequate annual inspections of Load Break Switches. I would be very interested to hear what people do for initial grounding testing, as well as follow up inspections. We currently build a 4/0 ground grid with 4 driven ground rods, then perform ground step potential tests. Thanks in advance for any info.

 

[apowerengr]

At what voltage levels? Do you model the GPR of the switch grounding installation? Switch grate (steel grid bonded to the ground which the operator stands on when operating the switch)? Gloves can insulate the operator if rated for the exposure (distribution voltage levels) whereas transmission voltages need supplemental protection (equipotential zone).

 

[vtpower]

apower, The voltages range from 12KV to 34KV distribution. Often times we can not use switch grates do to the location, i.e. in town sidewalks, mowed lawn. On the transmission and especially in subs, we use the grates. The field personnell always wear gloves when operating switches, so the issue is mainly a step potential issue. We do not model GPR currently, (do you mean with software?)

Thanks,
VT

 

[waross]

Consider portable gradient control mats. These perform the same function as a grate.
The ground conductors are connected to the switch handle. In the event of elevated potentials on the switch handle the workers feet will be held at the same potential as his hand.
respectfully